Concentration of supermicron and submicron aerosol particles in elementary school classrooms in Prague
Abstract
The present work deals with both numerical and mass concentration of aerosol particles measured in three classes in one school located downtown Prague. Classes were chosen with regard to specific activities held inside.
During working days, supermicron mass concentration of aerosol particles was higher than outside of the school building , which was probably caused by resuspension during lessons. Within 24 hours, the value of the ratio of the mass concentrations of I / O sub-micron particles were predominantly below the value of 1, while during the morning ratio was increased above 1.At the evening ratios of all the particles in the classroom decreased due to particle sedimentation and deposition and a ratio of I / O acquiring sub-micron particles was higher.
During the night, the coarsest particles had very low levels of I / O becase, opposed to submicron particles, poorly penetrate into the room from the outside air ( Figure 1 ). Multivariate analysis RDA was chosen for analysis due to blurred transition between sub-micron and supermicron particles and measuring two variables (mass and numerical concentration ) in submicron particles.
To shielding the effect of outdoor concentrations , these concentrations in the model chosen as covariates. The results showed that students had a significant effect on particle concentration (p -value < 0.01).
The strongest effect was seen in the mass concentration of supermicron particles a numerical concentration of submicron particles , while the mass concentration of submicron particles almost did not respond to classroom activity ( Figure 2 ). The relationship between concentrations and number of students in the classroom is statistically significant but relatively weak (student explained 5.97 % of the model).
Other variables were excluded from the model because their contribution was insignificant ( ventilation, CO2 concentration , the influence of the classroom and season ) .